Various ways of producing chewing gum tablets are known within the art, both with respect to the applied basic ingredients and with respect to the methods by which the final chewing gum tablets are made.
Thus, conventional chewing gum may for example be prepared by initial preparation of a gum base by mixing of water-insoluble ingredients such as elastomers and resins, typically under pressure and raised temperature. Secondly, the chewing gum ingredients, typically the water-soluble ingredients and for example flavor are added to the gum base, again by mixing. The final tablet may then be provided by a simple forming of the final chewing gum mix into the desired chewing gum tablet forms, e.g. by a kind of compacting. The above-mentioned process may be performed on a continuous basis or on a batch basis.
Such type of chewing gum is typically preferred when addressing the broad consumer market, or large-scale production, among many reasons due to the very advantageous texture of the final product. Hence, for many years this method has broadly been preferred.
An example of such chewing gum is described in U.S. Pat. No. 4,847,090, in which at least one preprocessed string of final chewing gum mixture is laminated or gathered together with another layer of different compositional character.
Another method applied, which is basically very different than the above described, may broadly be described as an initial conventional mixing of the gum base, as above described followed by a granulation of the obtained gum base mix. The obtained gum base granules may then be mixed with further chewing gum ingredients, such as sweeteners and flavor. This final granules mix may then be compressed under high pressure (typically when applying cooling) into to a chewing gum tablet.
This type of chewing gum, tableted or compressed chewing gum, has been widely used especially within a segment of medical chewing gum due to the thereto-related relatively careful way of handling the chewing gum ingredients and especially the active ingredient typically being quite vulnerable to for example high temperatures.
The present invention deals with the last mentioned type of chewing gum, the compressed chewing gum.
Typically, as mentioned above, compressed chewing gum has been acknowledged as quite suitable for the use of vulnerable ingredients.
One problem of the above-mentioned compressed chewing gum is that the chewing gum may be relatively expensive in manufacture and moreover, if a further processing is desired, such as coating of the final tablet, the initially gained benefits may be somewhat lost due to increased manufacturing costs and even worse, due to the stress- and temperature invoked weakening of the tablet during coating.
A further problem of the above-mentioned compressed chewing gum is that undesired interaction between chewing gum ingredients restricts the possible variations and applications offered by the technique.
A chewing gum tablet of the above-described type is disclosed in DE 28 08 160. The disclosed chewing gum tablet is obtained by compression of a chewing granulate, and the tablet may be formed by several different layers of chewing granulates mixed with different ingredients, such as sweeteners or active ingredients. A problem of the disclosed tablet is that the requirements to the mixture of the different layers are somewhat strict in the sense that all the layers are made on the basis of chewing gum granules mixed with different ingredients. In other words, chewing gum granulates must be present in a substantial amount in each layer, thereby restricting the choice of ingredients and especially the possible concentrations.
It is an object of the invention to obtain a compressed chewing gum suffering from few or none of the above-mentioned disadvantages.